Relay



June 15, 1943. H M STOLLER 2,321,710

RELAY Filed Sept. 26, 1941 f-/a T /M/E/VTOR T H M; S TOLLE l? A TTOR/VEV Patented June 15, 1943 RELAY Hugh M. Stoller, Mountain Lakes, N. Jassignor to Bell Telephone Laboratories, Incorporated, New York, N. Y.,a corporation of New York Application September 26. 1941, Serial No.412,360

Claims.

This invention relates to relays and more particularly to a combinedline and cut-off relay assembly for use on subscribers lines oftelephone systems.

In telephone systems and particularly in systems of the step-by-steptype, each subscribers line is provided with a line relay and a cut-offrelay, the two windings of the line relay being energizable in a circuitextending from the terminals of the centra-l oflice battery over twopairs of normally closed contact springs comprising a part of thecut-olf relay and the calling line loop when the calling subscribercloses the line loop at his substation to initiate a call. The linerelay upon energizing is instrumental in closing two pairs of contactsprings, over one pair of which a circuit is established to start anidle` line finder in search of the calling line and over the other pairof which the winding of the cutoff relay is connected to the test orsleeve conductor of the calling line terminating in multiple bankterminals of all line finders having access to the calling line. Whenthe started line finder nds the calling line and its test brushencounters the test multiple of such line, the circuit prepared by theoperated line relay for the cut-off relay is completed and the cut-offrelay operates to open its two pairs of normally closed contacts tothereby disconnect the windings of the line relay from the calling lineloop. It also closes a third pair of contacts whereby the cut-off relaylocks itself to the circuit completed over the test brush of the linefinder and is thus maintained operated following the release of the linerelay resulting from the disconnection of the windings thereof from thecalling line loop.

Some suggestions have heretofore been made for combining line andcut-off relays into a single unit to effect savings in manufacturing andinstallation costs andtto effect a ysaving in i mounting space on theapparatus rack at the central office. Since several thousand of bothline and cut-off relays are required each year, to meet the normalexpansion of installed telephone omces and to meet the normal demand fornew office installations, it is apparent that a relay structure thatwould perform all of the functions of both the usual line and cut-offrelays in a reliable manner and which could be simplified to such anextent as to effect material manufacturing, installation and maintenancecosts would be of great value.

It is therefore the object of the present invention to simplify thestructural details of a combined line and cut-off relay assembly, to

reduce thereby the cost of manufacture, installation and maintenance andto effect more reliable operation.

To attain this object and in accordance with one feature of the presentinvention, the magnetic circuit of the assembly comprises achannel-shaped field piece having two cores extending from the base ofthe channel forwardly between the flanges thereof upon-one of which issupported a two-winding line relay coil and upon the other of which issupported a cut-off relay coil. To complete the magnetic circuit, twoarmatures are provided which are pivoted on axes extending at rightangles to the flanges of the channel and which are attractable towardthe forward edges of the channel flanges and toward the pole face endsof the cores. Supported on the upper flange of the field piece are twospring pile-ups associated respectively with the two armatures. Foractuating the springs of the associated spring pile-up, each armature isprovided with a forwardly extending arm having a spring operating studof insulating material secured therein.

In accordance with a further feature of the invention, a short-circuitedwinding in the form of a copper sleeve surrounds each core and isinterposed between the core and the coil supported on the core. Thecopper sleeve on the line relay core is provided to render the linerelay slightly slow to release its armature to thereby insure that thecut-off relay will have suflicient time to close its holding circuitbefore the line relay releases its armature in response to the openingof the loop circuit over the subscribers line by the attraction of thecut-off relay armature. The copper sleeve on the cutoff relay corepermits the current to build up quickly in the test circuit establishedthrough the winding cf the cut-off relay and the winding of the testrelay of the line finder at the instant the line finder finds theterminals of the calling line. Heretofore the quick building up ofcurrent throughthe winding of the` cut-off relay has been accomplishedby the connection of a resistance of approximately 2800 ohms in shunt ofthe cut-off relay winding and by mounting Such resistance as anon-inductive third winding of the line relay coil. The provision of thecopper sleeve on the cut-off relay core permits the quick building up ofcurrent through the cut-off relay coil by inductive instead ofconductive coupling and avoids the more expensive non-inductive windingand the consequent necessity for dissipating the heat therefrom. Anadditional advantage attained by the omission of the shunt resistance isthat all of the current then passes through the cut-off relay coil andthe required ampere turns can be developed with a lower resistance,cheaper winding.

Other features of the invention will be apparent from the detaileddescription taken in connection with the accompanying drawing in which:

Fig. 1 is a perspective view of av relay assembly in accordance with thepresent invention with the spring pile-ups, one armature and onebackstop arm omitted and one of the relay coils shown partly in crosssection to more clearly illustrate a novel feature of the invention;

Fig. 2 is a perspective view of the upper portion of the relay assemblyillustrating the mounting of one of the spring pile-ups; and

Fig. 3 illustrates diagrammatically a circuitv application of theimproved -relay assembly.

Ihe relay assembly is provided with a channelshaped field piece memberI` which is bent into the shape best disclosed in Fig. 1 from a blankpunched from a sheet of magnetic iron. The member I has a base portion2, an upper flange 3 and a lower flange 4. The upperilange 3 is providedwith two portions 5 and 6 bent upwardly from its opposite ends to formbrackets to which the spring pile-ups are secured. The base portion 2 ofthe field piece member I is provided with two holes (not shown) in whichthe rear ends of two cores I are secured. After the cores are secured inplace, thev forward edges of the flanges 3 and 4 and the forward ends ofthe cores I are ground or machined to be in good alignment.

Each core 'I is surrounded by a tubular copper sleeve 8 the rear end ofwhich is knurled to hold the rear spoolhead of a coil, the core beingknurled near the rear end thereof to hold the sleeve thereon. The coil 9mounted on the lefthand core I as viewed in Fig. 1 is a cut-olf relaycoil having a single winding secured as by pyroX- ylin cement to therear spoolhead I which may be of suitable insulating material,l such asphenol bre, and which may have two-winding terminal lugs (not shown)secured thereto in the usual manner and extending rearwardly through anopening provided therefor in the base 2 of the eld piece member I. Thecoil I'I mounted on the right-hand core 'I is a line relay coil havingtwo equal windings secured to a rear spoolhead similar to the spoolheadI0 and having fourwinding terminal lugs secured thereto and extendingrearwardly through the opening in the base 2.

Associated with the forward ends of the core 'I are two armatures I2 andI3 stamped from magnetic iron. The armature I3 has been omitted fromFig. 1 to enable a clearer disclosure of the structural details ofthecut-off relay coil 9. Each armature is provided at its upper and loweroutside cornersy with cut-away portions to form two aligned andvertically extending pintles I 4k and I5 and with an arm I6 extendingforwardly at right angles therefrom to serve as a member for operatingcertain springs of an associated spring pile-up. The arm I6 has aportion I'I which extends above the plane of the upper flange 2 in theouter end of which is secured a spring operating stud I8 of insulatingmaterial, such as hard rubber. The two armatures I2 and I3 are similarexcept that they are reversely stamped and bent. The lower pintles I5 ofthe two armatures are seated in holes I9 in the forwardly extending armsof a U-shaped pivot plate which may be welded or otherwise secured byits base to the inner face of the lower flange 4. In welding the plate20 to the flange, the ends of its arms are permitted to extendsuiliciently beyond the forward edge of the lower flange 4 so that whenthe pintles I5 of the armatures are inserted through the holes I9, theywill be permitted to turn freely but will be held against undueseparation from the edge of the lower flange. The upper pintles I4 ofthe two armatures are seated in holes ZI' in the forwardly extendingarms of an upper U-shaped pivot plate 22. The plate 22 is secured by itsbase to the outer face of the upper flange 3 by screws 23, in such aposition that when the pintles I4 of the armatures are inserted throughthe holes 2|, they will be permitted to turn freely but will be heldagainst undue separation from the edge of the upper flange. The plate 22is provided at each end thereof with a forwardly extending arm 24 bentto lie in a plane at right angles to the base portion of the plate andserving as al backstop for the associated armature.

A spring pile-up is secured to each of the upwardly extending brackets 5and 6 of the member I.V The spring pile-up associated with the linerelay armature I2 comprises two fixed springs 25 and 26 and twocooperating, movable or armature springs 2'I and 28. These springs areclamped to the bracket 5 by screws 29 which extend through aligned holesin an outer clamping plate 3l), in the springs, in the spacers 3l, 32,33 and 34 of insulating material, such as phenol fibre, which areinterposed between the springs and between the outer spring 26 and theouter clamping plate 39, in the metal spacer 35 and into threadedy holes36 in. the bracket 5. The pairs of springs 25 and 21 and 26 and 28 havetheir cooperating contacts normally disengaged. The screws 29V wherethey extend through holes in the springs may be insulated therefrom bythe usual sleeves of insulating material which surround the shanks ofthe screws. The other spring pile-up associated with the cut-off relayarmature |3comprises three xed springs 3l, 38 and 39 and threeassociated movable or armature springs 45|, 4I and 42 as disclosed inFig. 3. These springs are insulatedly secured to the bracket 6 in thesame manner as the springs of the other pile-up. 'I'he pairs of springs3l and 40 and 3B and` 4I have their cooperating contacts normallyengaged and the pair of springs 39 and 42 have their cooperatingcontacts normally disengaged. Each spring terminates at its rear end ina soldering terminal to enable external Wiring conductors to beconnected therewith and each movable or armature spring has its contactend bifurcated with a contact welded to each section thus formed, thepair of contacts on each spring cooperating with a pair of contactswelded to the associated xed spring.

As best disclosed in Fig. 3, the insulating stud 53 secured to the armof the line relay armature I2, engages against the outer face of thearmature spring 2'I. Aligned with this stud and secured to the otherarmature spring 28 as by ring staking, is an insulating stud 43 whichextends freely through a hole in the fixed spring 25 with its outer endengaged against the spring 2l. Thus by the attraction of the armature I2assoelated with the une relay C011 ll, the studs ls and 43 cause themovement of the armature springs 21 and 28 to engage their contacts withthe contacS Of the associated xed springs 25 and 26.

The insulating stud I8 secured to the arm of the cut-off relay armatureI3, passes freely through a hole in the xed spring 31 with its free endengaged against the outer face of the armature spring 49. Aligned withthe stud I8 and ring staked or otherwise secured to the armature spring4I is an insulating stud 44, the outer end of which passes freelythrough ahole in the xed spring 38 into engagement with the inner faceof armature spring 40 and the other end of which is engaged against theouter face of the armature spring 42. Thus by the attraction of thearmature I3 associated with the cut-01T relay coil 9, the studs I8 and44 cause the movement of the armature springs 40 and 4I to disengagetheir contacts from the contacts of the associated xed springs 31 and 38and to engage the contacts of armature spring 42 with the contacts offixed spring 39. The armature springs are all so pretensioned thatthrough the insulating studs I8, 43 and 44, they normally press the armsof the two armatures I2 and I3 against the backstop arms 24 in whichposition, the inner edges of the armatures are separated from the frontedges of the flanges 3 and 4 by suitable air-gaps.

3 illustrates the application of the improved relay assembly to asubscribers line of a dial switching system served by a line nder. Inthis figure, the relay assembly has been schematically disclosed tobetter illustrate its operation. A subscribers substation is illustratedby the circle 45, the line finder by the brush set 46 and the test relayof the line finder by the rectangle 41. In the installation of the relayassembly, two terminals of the line relay coil II are connectedrespectively to the battery and ground busbars of the central officebattery and the other two terminals are connected to the armaturesprings 40 and 4I. One terminal of the cut-off relay coil 9 is connectedto the battery bus-bar and the other terminal is connected to the twoarmature springs 28 and 42 and to the sleeve multiples 48 of thesubscribers line appearing in the banks of all connector switches havingaccess to such line. The springs 31 and 38 are connected to the ring andtip conductors 49 and 58 of the line, the springs 26 and 39 areconnected to the sleeve or test multiples I of the line in the banks ofall line-finder switches having access to such line, such for example asthe switch 46, and the springs 25 and 21 are connected to theline-finder start circuit 52 and to ground respectively.

With the relay assembly thus connected, when the subscriber atsubstation 45 removes his receiver from the switchhook to initiate acall, a circuit is established from ground through the right winding ofline relay coil II, over the normally closed contacts of springs 38 and4I, tip conductor 59 of the calling line, over the line loop through thesubstation 45, and thence returning over the ring conductor 49, over thenormally closed contacts of springs 31 and 4I) to battery through theleft winding of line relay coil II. Coil I I thus becomes energized toattract the associated armature I2 to thereby move armature springs 21and 28 to engage their contacts with the contacts of the fixed springs25 and 26, respectively. The engagement of the contacts of springs 25and 21 closes the line-finder start circuit 52 to start an idle linender in search of the calling line and the engagement of the contacts ofsprings 26 and 28 prepares an operating circuit for the cut-off relaycoil 9 which may be traced from battery through such coil, over thecontacts of springs 28 and 26 to the sleeve or test terminal 5I therebyplacing potential on such terminal and the multiples thereof to indicateto a started line finder that the line is in a calling condition.

It will be assumed that the line finder indicated by the brush set 46 isstarted to hunt for the terminals of the calling line. As soon as thetest brush 53 engages the test terminal 5I of the line, the previouslytraced circuit through the out-off relay coil 9 is completed through theWinding of the line-finder test relay 41 to ground. Coil 9 thereuponenergizes, the copper sleeve 8 on its core permitting a quick build-upof current through its winding whereby the test relay 41 is enabled tooperate quickly. With the coil 9 energized, the associated armature I3is attracted to disengage the contacts of springs 4U and 4I from thecontacts of springs 31 and 38, respectively, to thereby disconnect thewindings of the line relay coil II from the calling line loop and toengage the contacts of spring 42 with the contacts of spring 39. Withthe contacts of these latter springs now engaged, a holding circuit forthe cut-oir relay coil is established from battery through such coilover the contacts of springs 42 and 39, test terminal 5I, brush 53, toground at the line nder to hold the cut-01T relay energized after itsinitial operating circuit is opened at the contacts of springs 26 and 28by the retraction of the line relay armature I2. Since the core of theline relay is provided with a copper sleeve, the retraction of the linerelay armature, whereby the contacts of springs 26 and 28 become opened,is delayed for a suiiicient interval to insure that the holding circuitfor the cut-off relay coil 9 has been established by the engagement ofthe contacts of springs 39 and 42. Cut-off relay coil 9 is nowmaintained energized over its holding circuit until the line finderbecomes released following the restoration of the receiver to theswitchhook at the calling line substation.

While the relay assembly has been disclosed as applied to a subscribersline terminating in the bank of a line nder, it will be apparent that achange in the arrangement of the springs of the spring pile-ups wouldenable the relay to be used in other types of dial switching or manualsystems.

What is claimed is:

l. In combination, a line relay having a magnetic circuit including acore and an armature attractable thereto, Contact springs operable bysaid armature and a cut-off relay having a magnetic circuit including acore and an armature attractable thereto, contact springs operable bysaid armature, and a copper sleeve on the cut-off relay core to enable aquick build-up of current in the cut-off relay coil.

2. A combined line and cut-off relay assembly comprising a field piece,two cores secured thereto, a line relay coil supported on one of saidcores, a cut-01T relay coil supported on the other of said cores,armatures attractable to the ends of the respective cores, contactsprings supported on said eld piece, certain of which springs areoperable by the cut-off relay armature and others of which are operableby the line relay armature and a copper sleeve on the cut-ofi relay coreto enable a quick build-up of current in the cut-01T relay coil.

3. A combined line and cut-off relay assembly comprising achannel-shaped iield piece, two cores secured to the base thereof andextending forwardly between the anges thereof, a line relay coilsupported on one of said cores, a cut- OIT relay coil supported on theother of said cores, armatures attractable to the forward pole-pieceedges of the flanges of said channel and to the ends of the respectivecores, contact springs supported on one of said flanges, certain ofwhich springs are operable by the cut-off relay armature and others ofwhich are operable by the line relay armature and a copper sleeve on thecut-01T relay core to enable a quick build-up of current in the cut-offrelay coil.

4. A relay having a magnetic circuit including a core and an armatureattractable thereto, contact springs operable by said armature, anoperating coil supported on said core and energizable in a circuitincluding another relay and a copper sleeve on said core interposedbetween said core and said coil to provide a quick build-up of currentin the circuit of said coil.

5. A relay having a magnetic circuit including a core and an armatureattractable thereto, contact springs operable by said armature, anoperating coil supported on said core and energizable by the entirecurrent applied thereto over a circuit including another relay and acopper sleeve on said core interposed between said core and said coil toprovide a quick build-up of current in the circuit of said coil.

HUGH M. STOLLER.

